docs: def add_word(self, word, value):
  		"""
  		Adds word and associated value.
  
  		If word already exists, its value is replaced.
  		"""
  		if not word:
  			return
  
  		node = self.root
  		for c in word:
  			try:
  				node = node.children[c]
  			except KeyError:
  				n = TrieNode(c)
  				node.children[c] = n
  				node = n
  
  		node.output = value